كيف احمي الخلايا بخصائص معينة

Private Sub Worksheet_Change(ByVal Target As Range)

If Not Intersect(Target, Range("a1:d10")) Is Nothing Then
With ActiveSheet
    .Unprotect
    .Cells.Locked = False
    For Each Cell In ActiveSheet.UsedRange
        If Cell.Value = "" Then
            Cell.Locked = False
        Else
            Cell.Locked = True
        End If
    Next Cell
    .Protect
End With
End If
End Sub